This invention relates generally to systems and methods for controlling medical devices, and more particularly, to a control system and methods for controlling tissue ablation.
Many medical treatments involve the removal of diseased or damaged tissue from within the body. For example, common surgical practice requires the excision of tumors, cysts, and polyps, which may appear in any area of the body, and the removal of atherosclerotic plaque from arteries. Classical surgical techniques require a properly trained surgeon to directly view the tissue being treated to determine which, and how much, of the tissue can safely be removed. This type of procedure is highly invasive and typically requires a lengthy recovery period for the patient.
More modern, less invasive surgical tissue removal techniques are known. Generally these techniques greatly benefit the patient, but present new challenges for the surgeon. For example, catheters, endoscopes and laparoscopes are now commonly used for a variety of surgical procedures and require minimal entry into the body. Use of these techniques generally decreases surgical trauma and recovery time, and improves outcome, but also incur significant disadvantages for the surgeon. Particularly, such techniques impair visualization of the affected region and substantially limit surgical working space. For example, optical fiber endoscopes are known but cannot be used in a blood field without first clearing the blood with a saline solution. Ultrasound probes are known but often produce false echoes when used for looking forward through, for example, the lumen of an artery. Fluoroscopy is known but is two-dimensional and exposes the patient and medical personnel to various forms of radiation.
Impaired visualization of the surgical field makes removal of diseased tissue difficult. In particular, the use of high energy tissue ablation devices such as those powered by lasers, radio frequency transmission, microwaves and the like, is risky under conditions of impaired visualization because poor discrimination of healthy tissue from diseased tissue can result in damage of healthy tissue. Accordingly, a surgeon operating such an ablation device must advance it extremely cautiously, perhaps missing diseased tissue which should be removed.
It would therefore be desirable to provide a precise and reliable method for controlling the activation and advancement of tissue ablative devices. It would also be desirable to provide an improved method for visualizing internal body tissues being treated with minimally invasive tissue ablative devices. It would also be desirable to provide an improved method and apparatus for differentiation of abnormal tissue from normal tissue.